"Mama" (finally!)

We (well, mostly Erin) have spent literally months unsuccessfully prompting Will to say 'mama'. Usually Erin would ask him: "can you say ma-ma?" and he would reply "DADA!" or with some other nonsensical stream of phonemes.
I'm not really claiming he knows what he's saying yet, but it has been fun that the hard 'd' was one of the first consonants he was able to pronounce, so 'dada' has been pretty much his default announcement. He picks up a new consonant every few weeks and works on that for awhile: recently he's been big on "ga", "gwa"/"cwa", "la", and "ra". He tries them with emphasis on different parts of the sound, at different pitches, and at different volumes.
Yesterday, I was changing Will's diaper and he said, very softly: "mehmeh". I was so excited I got Erin and we tried for awhile to get him to repeat it. He didn't (he gets stage fright sometimes) so Erin didn't believe me. Then later in the day he let another 'mama' out, then 'mamamamamama', and by the end of the day (and more this morning), he was droppin' 'mama's all the time.