I'm 3 months post-op, is it normal for hair to come in unevenly?

This looks just as it should for three months post-op. The permanent growth should continue to fill in and become more even over the next few months.

Growing unevenly in the 3rd month can happen but too early to say if it's a good or bad result. Hitting your head shouldn't damage the graft if no bleeding.

Regrowing hair is thin, undersized and not bright untill 4-5 th months of hair transplant. İt's normal for new growing hair starting to get native characteristics, waviness, curl in first 6-7 months..This actually takes 10-13 months for hair to become full mature , as thick and bright  as native hair. If you have not a bleeding and blood came out after you bumped up your head probably you may not missed a couple of grafts with dislodgement of them. 

Your hair growth looks to be fine at 3 months with variable degrees of growth as expected by the individual grafts at such an early stage. 

Its normal for hair to grow in at different rates. At 3 months its too early to see the results. Before and afters should be taken at 1 year.

hair growth after a hair transplant may come in unevenly but the lagging grafts will catch up with the other grafts. The trauma will not cause a problem