orange roots!

Hello, i dyed my hair to brown, my natural color, after it started looking red.  No problems.  The sun makes my brown hair look lighter and red.  I have dyed it many times, without problems.  My hair from the crown of my head down is light brown, the roots on the tip top of my head are looking a bit orange.  I am not sure why my hair is doing this?  Any ideas?  I am 7 months pregnant, so i am wondering if maybe that is not why.  I usually dye my hair at home and never have any orange roots.  And i always use revlon, and light ash brown?  I called the revlon place, they have no idea they just apologize.  it is not badly orange, but i can see that my roots are on the orange tint side.?????????????????????