Bottom section of mast fell out when carrying my gear up a hill, rolled down... and now the bottom section has a small chip about 2mm, on the outside of the mast at the very bottom where the extension goes. There is no visible sign of any cracking, just the outer section of the carbon laminate has some damage.

I am hoping that the damage, is in a low stress area, and the extension will extend at least 10cm into the mast and from where the chip is. Is this worth re-enforcing? and what is the best way to go about it?

The bottom of the mast is a high stress area, this is where splitting starts from extension loads.
Carbon doesn't like impacts, and there's possible damage there you can't see.
Epoxy by itself won't help much, you need to get some fibres involved.

I'd say without seeing it, it's a 50/50 situation, you may get away without repair, but you may not.

My repair, would be to fill the crack with an epoxy bog, (qcells in epoxy). sand a 10mm wide strip around the base and with epoxy wind a few layers of fibres around the base. Carbon or glass roveings with a layer of cloth on top. then wind a plastic strip on top of that to smooth it out and remove surplus resin. tape that tightly in place until resin sets.