Should I change my motor oil (possible dirt)?

[doublebase]

If it worries you that much, pour a little bit of fresh oil on the dipstick and slowly put it down the dipstick tube...pull it out and wipe it off. If there's dirt in there it will stick to the oil on the dipstick. Repeat a few times.

Personally I wouldn't worry about it though, there's more cars driving around on the roads every day with tears or loose connections in their air snorkels, letting stuff in than what possibly went down your dipstick tube.