If this happened in the UK and the elderly man reports being knocked over and scared by your dog, and he is on the lookout for you, you could be charged with having a dangerous dog out of control.
In the UK the law on dangerous dogs is VERY strict and a dog only has to give someone a big fright in some way, when out on public, for it to be classed as dangerous, and ordered to be muzzled and on the lead when not on it`s own premises.
If you are in the US, laws may be a lot different. I cannot comment on them.
GSD owner for 56 years (UK)