This evening I pulled nine Music from one corner of the bed, which included one of the short plants and others of various heights. I laid them out in order of height - smallest bulb is from the extra short plant on the far right in the picture. However the less extreme height variations don't seem to be especially correlated with bulb size - the stem thickness is a better indicator.
The small bulb is splitting open and pink. I lifted two more of the short/stunted plants and they are pink as shown in the pic, into the interior wrappers, and also small.
The pink color and splitting wrappers is a problem I have seen before and associated with wet weather or overwatering - as happened to a friend of mine last year. I have not been able to find anything like this on the internet so not sure what causes it, other than the wet conditions. It seems that the short/stunted plants were affected by the wet weather early on, and the "pinks" were severe enough to stunt them and produce a smaller bulb. A few larger bulbs were also affected by similar damage, but it did not stunt the plant, so perhaps it affected them later.
Anyway, the long story short is that short plants are indeed a sign of something wrong.
