I have had a similar problem with mine, but I always attributed it to the times when I didn't give her quite the gas she needed and that's when I noticed it. Does that sound similar to your problem? Only happens when I give a little less than normal throttle accidentally when letting clutch out in first gear. I know it sounds like a dumb thing to say..like hey dummy, give it more gas duh...but it seems like a little more than that, maybe there is a hesitation.
Another issue I have is when I put the clutch in between gears, I get a small rev instead of the RPM's dropping like they should when I get off the gas and on the clutch between gears...strange. I have adjusted by now and don't even notice, but whenever someone new drives it they notice it too.
A little background so you all don't think I'm nuts..I'm 41 years old and have been a car enthusiast since I was a teenager and have been driving standards and motorcycles and every other piece of machinery you can think of ever since. I know my stuff. This stuff with my car always grabbed me as a little strange, But never really enough to mention until now.
Bye the way, I run 87 with 93 about once a month.