How much was the exposure? Just a normal bin in which formaldehyde was stored? Or was it gaseous already? Generally just sniffing at an open bottle while being unpleasant should not have any serious effects. It was not during fumigation, was it (as the cabin should be sealed during that time)?
Generally the main dangers are that it is a potential carcinogen. While short term exposure can lead to the described symptoms, they vanish promptly (say 20 minutes or so). Long-term effects are usually only possible after long-term exposure. High concentration exposure on the other hand can be fatal, so it cannot be the reason, either.
Unless she was standing in the fumes for around 10 minutes with relatively high concentrations (something which one usually cannot tolerate voluntarily), formaldehyde poisoning alone is not likely the cause for lung problems.
However if she already had respiratory problems, it is possible that there was more damage than usual. I am afraid, I do not think that there is much info available for such special cases, though.