Knee problems

I was wondering if anyone could possibly tell me what may be going on with my knee.  I went to the gym yesterday and I bent down properly to remove a weight and put it on the ground and there was this sharp pain in my knee.  It wasn't really a pop cuz I could not hear it pop or felt it pop but it was a really quick sharp pain.  Not something that floored me or anything more of an annoyance.

After that I just shook it off and it never bothered me at all.  I lifted and did whatever.

I've had it happen to me before when I was trying to pick up a computer (I fix computers) properly by bending at the knees with my back straight and then lifting the computer with my knees instead of my back.

Each time it happens it's a relatively quick thing, again it isn't something so painful that I have to stop doing what I'm doing.  I just shake it off and continue doing whatever I'm doing.

Is it possible I have a knee problem?  I'd say it's happened 3-4 times total in a span of 5-7 years?

Also yesterday I was messing around and I was feeling my knee and I started doing a kicking motion where my knee bends and straightens and it eventually started to hurt midly.  Not hurt but I could tell it was annoyed/irritated.  Is this because I kept doing that or is there something going on in the knee that is making it do that?