Any nurses or MAs here?

I've been a medical assistant for a year now...
Today I gave a Tetanus (IM) shot to a patient and I did not aspirate. After I withdrew the needle, blood came out, like a not a little but not a whole lot. I figured I might of hit an artery. The site got swollen right away. I'm not gonna lie... I panicked, but proceed as usual, massaged a little and put the band aid on. The guy (18 y/o) didn't seem to be in pain or anything. I told him if anything he can get a little soreness and the site may get a little swollen so he could put warm compres on it. This is the first time that this ever happens. 
Will he be okay? Has this happened to anyone before?  I've been thinking about this all day long. The bump looked like a mosquito bite when you scratch it and it gets swollen. 
Please, no rude comments. I know I should've aspirate, and I will 100% of the times I give a shot from now on. That was something really stupid. 
Thank you.