I don't think there is anyway you could have compromised the gasket by putting the bike on the bench, unless the engine covers were loose to begin with, and putting it on the bench shifted the covers. I doubt it though.
Is the bike leaking from where the two halves of the engine meet or where the engine covers meet the motor? I'm assuming you're talking about the engine covers. I'd bite the bullet and replace both covers. Being a 1995, you may want to check your counter sprocket seal (looks like a thick o-ring) and your shift shaft seal (also looks like a thick o-ring). Both are cheap and easy to replace (I used a small hook and stabbed them and yanked them out).
You may want to look at your sprockets and chain while you have the left engine cover off. If you need new sprockets and chain, now would be the time to do it while you have the left engine cover off. When you reinstall the left cover, WATCH OUT FOR THE WIRES! You don't want to pinch them.