I do believe that is normal with most Tele sets. Especially if the neck pickup is covered and the polepieces are underneath the cover.
Usually the neck pickup sounds much more dull than the bridge pickup. For that reason, I rarely used the tone control when playing on the neck pickup of my Tele.
Eventually I disconnected the tone control from the neck pickup entirely and that sounds much better to me.
Of course I do use the tone control with the bridge pickup and when the two pickups are combined.
Try connecting the tone control directly to the bridge pickup.