phillyg wrote:
I'd suspect a problem with a bad seal, too much grease, bad and overheating brake or overheating bearing. Drive it and check all four wheel hubs with a temp gun, looking for a higher reading from the suspect wheel. Or, just tear it down looking for the problem.
The seal you're thinking about is on the back. Front either has a solid cap, bearing buddy or cap with rubber plug if there's a grease fitting on the spindle.
What the OP showed is typically not a concern. Little grease outside the cap or a little separated grease juice gets out sometimes and does that. If there's any real build up splattered then it may be leaking.