These two pictures are from the same plant. When I got it it had the solid red blooms and some buds on it. As the buds opened they were spotted. I have no idea why it did that, but it's one of my favorite regardless.
Also growing conditions can influence the colorings. Before you got it, the plant was used to one set of conditions - probably ideal greenhouse settings. Now you have the plant and conditions are most likely different. One major factor can be temperatures. Colder (not cold) conditions may influence brighter, deeper colorings.
I think it'll be interesting to see what the flowers look like the next time it blooms. I like the spotted just as much as the solid, the plant itself is growing great so I think it's plenty healthy. Guess I'll just keep watching to see what it does next.