Is this a sign of dominance?

[Alicia]

I've been very lucky in that all the sows I've had before have happily slotted together and lived together well. I now have 2 sows, Amber and Marmalade and I noticed today that Marmalade was chasing Amber a bit (not aggressively but just following her) and doing that purring noise that boars do. I panicked a bit and immedietly thought Marmalade was a boy or something because of the chasing and she also tried to mount Amber once but Amber just wheeked and walked off. I checked, and Marmalade is definetly 100% a girl, I asked other people too and they all agreed she was a girl. Is this dominance? Could this be a sign of them starting to fall out? Do I need to do anything or just leave them to it? I only saw it once but I just thought I'd ask because I've been thinking about it. They live near a boar, would they be competing for his attention? I know boars can do this.
I've watched them, and they're both eating food, hay and vegetables together and drinking water so I don't think one is stopping the other from eating.