It is not too early to worry but it is too late. 'It is what it is', and it is not going to change. The Panthers decided several weeks and possibly even several months ago that Bell would be the starting LT. Bell 'is who he is', and a large part of the success or failure of this season will be how he and the entire O-Line plays.
I will also say that Bell will need good play from his LG (Amini) who is coming back from a major injury. I sill believe that one of the reasons why Gross had such a great year last year was because his buddy Wharton played LG. Those two just worked well together, and it showed on the field.