Phone keeps making me enter my Apple ID

I asked about this in the past. But now cannot find any of those posts. Anyway, my iPhone is ANNOYINGLY forcing me to enter my Apple Login repeatedly (and Unlock My Account). It did it last night and now again tonight. I know for certain my password is very secure, so I refuse to change it. And besides, if I were getting locked out due to some person trying to hack into it, then it should be giving me longer wait times between attempts, but it is not. My password is a word, but using random upper/lower and substituting a number for some letters. For example, the word Alamogordo, but I might make that A!@m0G0rd0 I am getting very angry every time I have this hassle!