Hi, XXXXXXXXXX:
Yes, laminitis is possible at any time of year, as it is not only the fresh, spring grass that can cause an onset. Laminitis can also be brought on by different metabolic diseases, stress, diet changes and grain overload to name a few. This is especially true if there is a previous history of laminitis or if the horse/pony is overweight and possibly suffering from Cushing's disease or Equine Metabolc Syndrome.
If there is a chance that your pony is suffering from laminitis, please give your vet a call to schedule an exam. It's best to address the problem early before long-term problems develop!
Thanks, and best of luck!
Horse Veterinarian
Solo Equine Practitioner/Mobile Practice Owner for ten years.