About once a month, I get trouble sleeping. Is that ok or bad?

Ok. Occasional trouble sleeping is very common. If it starts to interfere with your activities or relationships, then talk to your doctor.
Sleeping Problems. I don't think this is abnormal but i would keep a diary of the days you have the problems. It could be related to your cycle, stress, caffeine, alcohol, medications, etc. I think you will figure out the time and the cause by paying attention to your diary. Hope this helps.