vertical grip mandatory?

I am not a competitive BE shooter. At my age and health, it ain't happening.  That said, I love shooting BE and am working on
getting back in shape after a really bad health year.   I noticed when dry firing that my natural grip results in the pistol being  slightly off vertical, say 5 or 10 degrees leftward tilt. That happens when my natural point of aim is pretty good, and it does not
seem to bother a good trigger break.
Is there a problem hiding here?

What pistol and grip?
Generally speaking you can adjust your gripping hand to move the sights to the right. 
1911 this is easier than euro type grip.
Does your elbow hyperextend or is it straight? Hyperextended elbows typically point sights low and left (right handed).
I should add, you do not want to force your position on the target. You cannot maintain a consistent forced position and shoot well. 
Jon

The only problem I can think of is that your sight adjustments can be more difficult, e.g. the elevation clicks now move the point of impact not only vertically, but laterally as well. 
I own a very interesting pistol, Morini CM80, it's a free pistol and both front and rear sights can rotate along the bore axis. This way shooters can have a tilted grip and the sights can still be vertical, so that adjustments move the point of impact only along one axis, X or Y.

One of the finest Bullseye shooters of the 60’s was John Hurst.  He tilted the pistol to almost 45 degrees at times.

In training with Brian Zins he brought up that canting the pistol can cause the gun to move horizontally a little more under recoil.  Instead of the gun going more vertical and coming back into the target from the same direction, it would be returning from the left more.

Ok, the pistols are Marvel conversion 22 on an LB frame with Nill grips, the big fat ones.   The other is a Tanfoglio Limited Master 45 large frame.  I like the fat grips and my only issue with 1911 is the confounded grip safety, which my gunsmith will set up for a higher initiation point, so I am not distracted with the safety not being depressed while pulling the trigger.  I have nothing but time, so maybe I will see about correcting the tilt a bit.

I have seen some people shoot with a cant and do quite well so I think it can be done. For me personally, if I concentrate on keeping the gun vertical, my shots tend to be better.  It could be that I’m concentrating more in general so the shot is better but in my mind, the perfect vertical hold is the reason.

Good luck.
John