The human body is a very strange mechanism. I don't think it's unheard of for someone on T to have it come back out of the blue. As Kreuz did say, it would be best to check with your endo or GP for the peace of mind, as I'm sure nothing is particularly wrong as you have been proactive in being consistent with your injections.
Try not to worry too much - I'm sure after you speak to your GP you will have a better perspective on the situation. It sucks that it happened, and I'm sorry to hear it did. I'm sure some other dudes on the forum have experienced a similar occurance.