Help with my friends.?

I am taking a smester off from college for minor health reasons, i was too bashful to tell all of my friends about it so I only told one, and hoped that the rest would contact me. they haven't, they only talk to me when I talk to them first. I thought they were bad friends because of this but now i realize it may be my fault because they may be mad at me that i did'nt tell them. and since they are strong, thick skinned, confident people they brushed it off. are they being bad friends or was i the bad friend. and what should i do to make it not awkward and still be friends with them next semester.