Should I be worried about the numbness in the lower lip on the left side, left chin and lower left teeth after moral#19 implant?

You need to follow up with your surgeon and have him/ her map the area and document the progression if any of the sensations coming back.  It is not a bad idea to take a CT scan after the surgery if haven't done so either.  If there is not major damage to the nerve, then the sensation should return eventually.
Dr.Aynechi

Its good that your implantologist changed your implant in to a shorter one . Usually there is a nerve running below the teeth in that region and any injury to the nerve canal takes about 8-10weeks or sometime much longer to heal . Please take a multi vitamin Tab called Neurobion daily once for 2 months it will help in healing faster .

Hello,
I am so sorry you have been experiencing post operative complications. There is a nerve that runs in your  lower jaw. There is always a possibility that this nerve was injured during implant placement.  During pre-operative discussions this is always brought to the paitent's attention. However most of the time the numbness and tingling wears off within 6 month to a year. Please bring it your surgeons attention that you are feeling like this if you do not see improvement soon. Best of luck.