Contas, if any of the channels touch the very right hand side of the histogram, that channel is likely blown out, especially when it "spikes".
If you shot RAW you may be able to just reduce exposure a bit to avoid this. If the "spike" is very large though this may not be enough, and you would've had to reduce exposure when taking the picture. Always check the histogram, especially flowers are tricky because there is a lot of detail in the highlights (even in just one or two colours, like my tulip shot above).
