Jim,
There could be a connection, but my guess is not pronounced. I found amphetamine-like action from Norvasc (amlopidine...a component in Lotrel)...this indicates it might be a bit thermogenic, and thus good for the waistline.
On the other hand it takes a great deal of energy to support high blood pressure...so my theory is that any effective BP drug MUST tend toward some weight gain.
Beta blockers which slow the heart and weaken its beat the most seem to be the worst flab-makers.
YES, edema (water retention) is a known and serious effect of calcium channel blockers (the amlopidine again.) Thus they work best combined with a drying diuretic. Check for swollen ankles and sock lines that take FOREVER to go away (I HATE that look!)