I have been off the pill after taking it for one year. (Diane 35). My platelet level was 388 one month ago and now it rose to 400. Should I worry?

No worries. There is considerable "wiggle" room in the calculation of blood levels of platelets. 388 and 400 are essentially the same and not a reflection of a trend or anything wrong. Why was your platelet count being done anyway. There should be a clinical need to get this value.