No period and tubes tied!

I know that is maybe so weird but I just want to know I had a set of twins 9 months ago and I got my tubes tied soon after they was delivered everything was going good and fine until I missed my period now this is the 1st one that I missed so my question is is it normal to miss cycles or a cycle after your tubes has been tied or what I know that it can mean a ton of other things but it's all kinda strange to me!?