I'm sure the mantras and the expectation to have a lucid later in the night helped. If you find that mantras and self affirmations work for you, take advantage of it. I've recently had a lot of success with autosuggestion type mantras. It is the easiest technique by far.

Also, if you notice you woke up 2 hours after your alarm was supposed to go off, maybe you had your alarm set for the wrong time. Try doing your next WBTB at the same time you had these lucids.