No, I'd say that's normal for those heaters,
I've had them in 5 gallons all the way down to 1/2 gallon sizes,
And as I said it will reflect the temp of the room they are kept into.
Ideally it would reach 78,
74 is far better then 64 and better then having a heater that may cook him...
My kids had several in their bedrooms that only reached that temp and the betta did just fine,
Thanks for the info. He is just super excited to be out of that little wal-mart cup. He looked so sad in there, I'm sorry I had to keep him in there for so long. But now he's been swimming around a lot and staying close to the heater also. :)