Slim, open space between stonework above window - fill in or leave?
I'm new to this forum and would very much love to get advice from you guys about a situation I'm dealing with that worries me. I've got a stone exterior home and two of the windows are having problems (that may not really be anything to worry about - I hope!) with the stonework separating from the metal above the windows. I'm assuming this is because the metal has warped over the years, or it could be due to water infiltration. I'd like to caulk the space to ensure that cold air and water don't get in over the winter, but I worry about the possibility of making it a bigger issue by doing so. What if the split was caused by water infiltration and sealing the space up would have the effect of making the water go further behind the stonework in other places? That could get serious and expensive. Or, am I worrying over nothing?
Attaching a pic here to show you guys what I'm talking about. Any input wold be greatly appreciated!